Tech Topic: Friends In Low PlacesLook at the principles behind cardioid subwoofer arrays, clearing up common confusions, and learning how to deploy these arrays in the field.By Michael Lawrence • November 19, 2018

Thanks to the proliferation of powered loudspeakers, active subwoofers sporting built-in “cardioid mode” DSP settings are on the rise. But what’s going on under the hood?

Let’s take a look at the principles behind cardioid subwoofer arrays, clear up common confusions, and learn how to deploy these arrays in the field.

Before digging into how to steer subwoofer coverage, let’s ask why we might want to do that. Unlike full-range loudspeakers, we can’t simply aim subwoofers in the direction we want the sound to go. It’s often repeated that subwoofers are omnidirectional, dispersing their acoustic energy in all directions. Throughout the frequency range in question, the wavelengths are so long (over 37 feet at 30 Hz) that the relatively small diameter of the loudspeaker cone can’t exert directional control over the output.

A valid objection to this statement would be that subwoofers definitely sound louder in the front. Although subwoofers are very nearly omnidirectional at the low end of the frequency range, the shorter wavelengths associated with higher frequencies means more directional control as frequency rises...

I've always had the idea that an offline scene editor would allow me to prepare for a show or a festival in the comfort of my home without having to drag out the mixer.

I had what I call a partial offline solution for the original Presonus 24.4.2, but did not do much with it because its functionality was so limited. I used to be holding my breath that A&H would offer one for their QU series.

With the rack mount mixers, they don't take up much space so my wife is less on my case than if I had a 32 channel desk set up somewhere.

What is your experience?

thanksfrank

I use the X32, Yamaha CL, GLD and AVID editors all the time to prep upcoming shows or musical theater productions. I typically have more time in the middle of the night (insomniac) or on a plane in route then I get when I am actually standing at the console to get things exactly as I like them. Using the editor also reminds what I may have forgotten about the console workflow if it's a model I have not used in awhile.

I recently upgraded from DSR's to RCF NX 45-A. (I got them new for a pretty healthy discount.) Wow! What a noticeable difference it made. It was as if someone had removed the army blanket from over my DSR's. The word clarity has a whole new meaning to me now. I'll never go back to MI gear.

EDIT: I still have (and love) the DSR's. I use them for stage monitors, delay fills, or those little SOS jobs. I also wanted to add that I believe the whole NX line sounds somewhat similar to one another.

I have asked Sennheiser's chief wireless engineer for a 1 rackspace integrated IEM Tx and Rx in one chassis with compatible frequency co-ordination and in typical German fashion he replied "Why would you want that ?" [...]

I suspect the reason he's sceptical is because, from an RF standpoint, this is actually a pretty tricky problem. Putting a transmitter near a receiver typically causes the receiver to desens and have reception issues. On the rack side this can be solved with proper antenna placement (although at that point your antenna rig takes up enough space that the 1U form factor is pretty moot); on the performer side things start to get tricky, especially if you want diversity reception for your IEMs (which you do).

The Telex BTR approach to this problem was to leave ~100 MHz between the RX and TX frequencies and then use filtering to reduce desens to manageable levels, but with available spectrum reductions this has gotten a lot harder. A shared antenna on the beltpack and a circulator would theoretically work, but you'd again lose diversity reception (and circulators tend to be delicate and expensive).

Probably the best solution is the most common: put a large bag of meat between the RX and TX beltpacks to attenuate the TX signal at the IEM RX. Of course, this means using a single beltpacks for both isn't possible.

Basically, as I understand it, what you're looking for doesn't exist because of physics...

I picked up a couple used Chauvet RGB Geysers. One has developed a clogged heater... oddly enough, this happened while I was running through a 50/50 Distilled Water/White Vinegar cleaning cycle.

I took the unit apart and verified there were no clogs leading up to the inlet of the heater. I also verified the pump was working.

I tried running a guitar string (tried E, A and D) through the heater, but it appears the path takes a lot of twists and turns. I ran the string into the inlet about 18" or so before I got scared of breaking it off inside the heater. It never did make it all the way through.

I tried tried forcing air, water, and vinegar into the inlet with a squeeze bulb, but never got it to come out of the outlet.

So far, none of this has improved the situation.

The last thing for me to try (that I can think of) is what was mentioned here- to use CLR. I pickup up some CLR, but it states on the bottle "Do not use on steam machines". For those of you who have used CLR with success, have you had any problems? Is there anything else worth trying?

I can only compare the DZR12 to the QSC HPR122i, which I mentioned in the other DZR thread. I used my DZR12s on a gig for the first time this weekend and they did not disappoint. FOE gig, no subs, ran 3 vox, fiddle, and electric guitar via Touchmix 16. Received comments about how clear everything sounded.

My reasons for buying the DZR12 over the DSR12:Side handles; I was able to install on stands by myselfNewer model (an expectation that Yamaha made improvements over the DSR)Greater control/flexibility over the DSR: Multiple HPF settings, delay, etc.

You must be new here. This has been documented extensively. Whatever Behringer did with the AES50 ports on those models requires ground continuity between Ethercon shells in addition to shielded RJ45. No other Midas or K-T products seem to have this absolute need.